Transparent glass microspheres and products made therefrom

Essentially colorless transparent glass microspheres that are less than about 2 millimeters in diameter, have an index of refraction between 1.90 and 1.95, contain less than 5 weight-percent of scattered crystallinity, and are at least 95 weight-percent bubble-free, said microspheres being free of alkali oxides, having a uniform index of refraction throughout a sample, and being free-flowing so as to be applicable in a uniform manner, whereby retroreflective products of maximum retroreflectivity are obtained, and said microspheres consisting essentially of between about 25 and 40 weight-percent TiO.sub.2, between about 42 and 65 weight-percent of heavy metal oxide selected from BaO and CdO, between about 10 and 18 weight-percent of glass-forming oxide selected from SiO.sub.2, P.sub.2 O.sub.5 and GeO.sub.2, and up to about 20 weight-percent of substituents from the table and within the proportions of FIG. 2 of the drawings;

• the proportions of the constituents in the microspheres defining points within the polygon MNOP of FIG. 1 of the drawings.